If you’ve outgrown your home and you can make it bigger by building an extension or converting the loft, cellar or garage, doing the work is often more economical than moving. It also gives you an opportunity to create space tailored exactly to your needs.That said, be careful not to get carried away and enlarge your home in the wrong way. For example, if you convert the loft into an extra bedroom or bedrooms and there isn’t enough living space downstairs for the total number of bedrooms, you’ll have made the house too top-heavy.It’s often said that the rooms that most sell homes are the kitchen and bathroom, because replacing them is expensive and disruptive so buyers don’t want to do it themselves. Swapping a dated kitchen or bathroom for a modern one will make a big difference to your everyday life, too, and you really don’t have to take out a second mortgage to pay for it.A good way to get a bargain kitchen is to buy inexpensive units and even cupboard doors, then spend more on the worktops - oak-block ones are stunning but needn’t be costly if you buy them online - and a statement tap and/or sink.Try your local DIY store for reasonable takeaway units - an IT Kitchens 1,000mm White Base Carcass is just £38 at B&Q, for example. Takeaway units are ideal if you’re in a hurry or not sure about the layout, because if you find you need one size instead of another, you can simply go to the store and get it. B&Q recently announced an end to ‘yo-yo’ pricing on kitchens, so customers will get good value all year round, not just during the sales. If you find a kitchen cheaper elsewhere, B&Q will, at the least, match the cost, as long as the kitchens are of a comparable specification.DIY stores are also a source of reasonable bathrooms - the cheapest takeaway basin, bath and close-coupled toilet are £171 in total at B&Q. Budget buys can be dressed up with nice tiles and taps - Mira Showers has a new range of beautifully designed and engineered bathroom taps (see www.mirashowers-store.co.uk).Adding bathrooms, especially an en suite, is a brilliant way to up value and make your home life easier, especially if there are too many people using the family bathroom. This is when an en suite for the main bedroom is invaluable. People sometimes think that having as many bedrooms as possible adds value, but it’s usually more valuable to have enough bathrooms for the number of bedrooms.It’s also useful to have a bathroom on every floor where there are bedrooms. Loft-conversion bedrooms with a bathroom or shower room are usually more valuable and useful than those without. In family homes, a downstairs toilet is a must, too, even if you have to squeeze it into a small space, such as the under-stairs cupboard.Another must for families these days is open-plan living space. Where once separate dining rooms and kitchens were popular, now the trend is for open-plan kitchen-diners/family rooms where the whole family can be together. However, totally open-plan space isn’t necessarily the best way to add value, or live day to day. Having a more formal sitting room, as well as a more casual room, works well for many families, so do get out your sledgehammer... but don’t go mad with it.